It is well known in the art that natural light is generally unpolarized and that various polarized states of a light wave exist, such as the general case of the elliptical polarization with its extreme states plane (linear) polarization and circular polarization. Further, various polarizing devices are known with which natural light can be transformed into totally or partially polarized light.
A plane polarized light wave, the electrical vector E of which oscillates parallel to an x direction of a Cartesian coordinate system and which propagates along the z axis, can be described by the following equations EQU E.sub.x =E.sub.0x sin(.omega.t-kz) and E.sub.y =0
wherein
E.sub.x and E.sub.y are the components of the electrical vector in x and y directions, respectively, PA1 E.sub.0x is the amplitude of the light wave, PA1 .omega.=2 .pi..nu. is the angular frequency of the light wave, PA1 .nu. is the frequency of the light, PA1 K=2 .pi./.lambda. PA1 .lambda. is the wavelength of the light wave within the medium through which the light wave propagates. PA1 E.sub.0x =E.sub.0y =A. PA1 A is the amplitude.
Right-hand (clock-wise) circularly polarized light can be described by the following equations EQU E.sub.x =E.sub.0x .multidot.sin (.omega.t-kz) EQU E.sub.y =E.sub.0y .multidot.cos (.omega.t-kz)
wherein
The above equations show that the polarization of a light wave is independent of x and y, i.e. that the electrical vector E has in each point of an xy plane, z=Constant, the same direction.
It is desirable for investigations of the interaction of light with matter, in which a cylindrical type of symmetry prevails because of the conditions of the experiment, to have a "cylinder-symmetrical" distribution of the direction of the electrical vectors of the light wave across the cross-section of the light beam or, in other words, such a distribution that the electrical vector has, at any point of a beam cross-section, either a radial or a tangential (azimuthal) direction with respect to an axis which is assumed to coincide with the z axis. For instance, such a distribution would facilitate the interpretation of experiments for investigating the interaction of laser light with a cylindrical plasma, and further may yield new effects which are totally different from those which are obtained by using plane, elliptically or circularly polarized or unpolarized light, because the magnetic field distribution of the light wave is quite different when the light is radially or tangentially polarized.